1. Technical Field
The present disclosure relates to a vehicle headlight device mounted to a vehicle, and particularly to the vehicle headlight device which reduces a burden of a vehicle operator when the vehicle travels in the dark.
2. Related Art
Headlight devices mounted to vehicles, such as automobiles, are typically configured to be provided with a plurality of lighting systems having different light distribution characteristics (e.g., different illuminating areas), for example, caused by high beam (driving beam) headlights and low beam (passing beam) headlights, of which light sources are selectively turned on and off according to a traveling state of the vehicles. Recently, Adaptive Front-lighting System (AFS) that automatically changes the illuminating area, for example, according to the traveling state of the vehicles has been proposed. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2014-008913 discloses a headlight device that reduces a glare to oncoming automobile(s), pedestrian(s), etc. by changing the intensity and angle of the illumination according to a traveling speed of the vehicles.
It is common that the conventional headlight devices are configured to illuminate within a preset illuminating area at an intensity (brightness) as uniform as possible. However, human tends to instinctively gaze at or keep his/her eyes on a bright spot within his/her field of vision. Thus, if the inside of the illuminating area is illuminated substantially at the same intensity, the person is uneasy to set his/her line of sight. Therefore, there is a problem that the tension of the vehicle operator increases, and he/she gets fatigued.